From 3b0f821fdefab9a775ddd602230edfe5336c01dc Mon Sep 17 00:00:00 2001
From: Dulma Churchill <dulmarod@fb.com>
Date: Fri, 18 May 2018 03:54:52 -0700
Subject: [PATCH] [retain cycles] Remove false positives about modelled types

Reviewed By: mbouaziz

Differential Revision: D8055558

fbshipit-source-id: 65d88d3
---
 infer/src/biabduction/RetainCyclesType.ml | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/infer/src/biabduction/RetainCyclesType.ml b/infer/src/biabduction/RetainCyclesType.ml
index ea6519c89..21fc0d3f6 100644
--- a/infer/src/biabduction/RetainCyclesType.ml
+++ b/infer/src/biabduction/RetainCyclesType.ml
@@ -73,6 +73,25 @@ let is_isa_field node =
       false
 
 
+let is_modelled_type node =
+  let modelled_types =
+    [ "NSArray"
+    ; "NSData"
+    ; "NSDictionary"
+    ; "NSMutableArray"
+    ; "NSMutableDictionary"
+    ; "NSNumber"
+    ; "NSString" ]
+  in
+  match node with
+  | Object obj ->
+      List.exists
+        ~f:(fun model -> String.equal model (Typ.to_string obj.rc_from.rc_node_typ))
+        modelled_types
+  | Block _ ->
+      false
+
+
 let _retain_cycle_node_to_string (node: retain_cycle_node) =
   Format.sprintf "%s : %s" (Exp.to_string node.rc_node_exp) (Typ.to_string node.rc_node_typ)
 
@@ -125,6 +144,10 @@ let normalize_cycle cycle =
 let create_cycle cycle =
   (*isa is an internal field not accessible or writable, so it doesn't make sense in a cycle *)
   if List.exists ~f:is_isa_field cycle then None
+    (* The modelled types, where the models are meant to catch NPEs or Memory Leaks, include fields
+     that don't necessarily reflect the real code, so potential retain cycles including them are
+     probably wrong. *)
+  else if List.exists ~f:is_modelled_type cycle then None
   else
     match cycle with
     | [hd] ->